WASHINGTON (AFP) - US President Donald Trump has congratulated Andres Manuel Lopez Obrador on his landslide victory in Mexico's presidential vote, saying he looks "very much forward to working" with the anti-establishment leftist.

"There is much to be done that will benefit both the United States and Mexico!" tweeted the US Republican leader, whose anti-trade, anti-immigration policies have plunged bilateral ties between the neighbours to a historic low.

Trump - who during his presidential campaign charged that some Mexican immigrants were "criminals" and "rapists" - early in his presidency ordered the building of a wall along the 3,200 km US-Mexico border.

More recently, Mexico slammed Trump for calling migrants "animals." The outgoing Mexican president, Enrique Pena Nieto, has twice canceled plans to visit Washington over Trump's ongoing insistence that Mexico pay for the wall.

The White House additionally is scrambling to calm international outrage over a Trump policy that had allowed the separation of migrant children from their parents at the border.

The brash US leader has also threatened to tear up NAFTA, the two-decade-old North American Free Trade Agreement.

Talks to renegotiate the terms of the pact between the US, Mexico and Canada have been bogged down by efforts to satisfy Trump's demands.

The sharp-tongued Lopez Obrador has promised to put Trump "in his place".

Canada's leader Justin Trudeau has also congratulated Lopez Obrador on his sweeping presidential vote win, citing "common goals" on trade and human rights advancements.

"Canada and Mexico are close friends and longtime partners. We share common goals, strong people-to-people ties, and a mutually beneficial trading relationship that is the envy of the world - reflected in our joint effort to update the North American Free Trade Agreement for the 21st century," Trudeau said in a statement.